1. Field of the Invention
This invention relates generally to a manual transmission gearshift mechanism for an automotive vehicle and more particularly to such a shifting mechanism for the control of a five forward speed transmission providing an interlock to prevent shifting other than into the gear ratio selected by the vehicle operator.
2. Description of the Prior Art
The gearshift mechanism of a manual transmission is generally provided with some means associated directly with the shifting action of the mechanism that prevents accidental movement of more than one gear into driving engagement at a time. Various means have been described in the prior art for selectively engaging various speed ratios of the transmission while providing an interlock. Prior art patents directed to gear shift mechanisms for four speed transmissions having an interlock include U.S. Pat. Nos. 3,202,005; 1,973,553; and British patent nos. 1,053,353; 1,038,591; and 1,008,556.
An in-line manual transmission having five forward speed gear ratios and a reverse gear ratio presents particular problems regarding the shifting mechanism because of the distance of the fifth forward speed from the shifting and interlock mechanism that controls the gear shifting sequence among the five forward speeds and the reverse speed ratio. An additional difficulty arises with respect to coordinating the interlock function of the fifth forward speed ratio and mechanisms for interlocking and controlling gearshifting among the four lower gears of the transmission. The prior art has taught the use of multiple shift rails for coordinating the movement of various shifting forks. The British patent No. 1,038,591 is a typical example of a control mechanism employing multiple shift rails. The five forward speed manual transmission having an overdrive speed ratio requires a simple, inexpensive and trouble-free mechanism for providing the interlock in gear shifting functions.